<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        // 声明变量
        let age = 18
        alert(age)
var num = 20
let uname = '张三'
console.log(num);
console.log(uname);
// 变量的改变   重新赋值
let name = prompt('请输入姓名这一块')
// 储存数据是通过声明变量
document.write(name)
// 交换变量
let a = 10
let b = 20

 let temp = a
  a = b
  b = temp
console.log(a,b);
let namee = prompt('请输入姓名:')
let agee = prompt('请输入年龄:')
let sex = prompt('请输入性别:')
document.write(namee)
document.write(agee,'岁')
document.write(sex)
// 数组用arr =【】 依旧从零开始
let arr = [1,2,3,4,5]
console.log(arr);
let arr1= ['周一','周二','周三','周四','周五','周六','周日']
console.log(arr1[6]);
// 常量就是不能变的量咯
const A = 12




    </script>
</body>
</html>